1. Field of the Invention
The present invention relates to a noise filter and particularly to a noise filter with an improved insulating case member.
2. Description of the Related Art
A noise filter is commonly used on a cable such as a high frequency transfer line for preventing electromagnetic interference (EMI). Normally, the noise filter comprises a pair of ferrite core halves which form an opening therebetween for a cable to insert therethrough and a pair of insulating case halves for respectively containing the ferrite core halves therein. A hollow ferrite core member can be detachably received in a corresponding insulating case member or can be formed integrally with the insulating case member by an injection molding method. The former kind of engagement between the ferrite core member and the case member is achieved only by a bud on the case member which prevents the ferrite core from being deviated therefrom. However, there is a possibility that a relative displacement of the ferrite core member to the case member will be occurred during a severe environment. In this situation, the effect of the noise filter for shielding the cable from EMI is influenced. Moreover, the construction of integral core member and case member will add difficulties to manufacture as well as increase the cost of products.
Hence, a noise filter with an improved case member is required to overcome the above-described disadvantages.
Accordingly, one object of the present invention is to provide filter with an improved insulating case in which a hollow ferrite core for inserting a detachable cable therethrough is firmly secured and is protected from damage.
Another object of the present invention is to provide filter with an improved insulating case which can be manufactured easily and cost-efficient.
A further object of the present invention is to provide a noise filter with an improved insulating case by which a cable received therein is secured.
To achieve the afore-mentioned objects, a noise filter comprises a hollow ferrite core and an insulating case covering the ferrite core. The insulating case is made up of a pair of case members the configurations of which are substantially symmetrical. A plurality of resilient ribs with sharp-angled tops and a plurality of support ribs are interlaced in an inner face of each insulatingcase member for providing a radial force to the ferrite core. Each case member has a front wall and a rear wall on which a dented top side is formed respectively. A plurality of serrated protrusions are arrayed on the dented top sides for positioning and securing a cable received in a hole of the ferrite core.
Other objects, advantages and novel features of the invention will become more apparent from the following detailed description when taken in conjunction with the accompanying drawings.